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lokinet/include/tl/optional.hpp
Jeff Becker 41e8691702
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2019-01-17 09:02:50 -05:00

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///
// optional - An implementation of std::optional with extensions
// Written in 2017 by Simon Brand (@TartanLlama)
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to the
// public domain worldwide. This software is distributed without any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software. If not, see
// <http://creativecommons.org/publicdomain/zero/1.0/>.
///
#ifndef TL_OPTIONAL_HPP
#define TL_OPTIONAL_HPP
#define TL_OPTIONAL_VERSION_MAJOR 0
#define TL_OPTIONAL_VERSION_MINOR 5
#include <exception>
#include <functional>
#include <new>
#include <type_traits>
#include <utility>
#if(defined(_MSC_VER) && _MSC_VER == 1900)
#define TL_OPTIONAL_MSVC2015
#endif
#if(defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 \
&& !defined(__clang__))
#define TL_OPTIONAL_GCC49
#endif
#if(defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 4 \
&& !defined(__clang__))
#define TL_OPTIONAL_GCC54
#endif
#if(defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 5 \
&& !defined(__clang__))
#define TL_OPTIONAL_GCC55
#endif
#if(defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 \
&& !defined(__clang__))
// GCC < 5 doesn't support overloading on const&& for member functions
#define TL_OPTIONAL_NO_CONSTRR
// GCC < 5 doesn't support some standard C++11 type traits
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
std::has_trivial_copy_constructor< T >::value
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
std::has_trivial_copy_assign< T >::value
// This one will be different for GCC 5.7 if it's ever supported
#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) \
std::is_trivially_destructible< T >::value
// GCC 5 < v < 8 has a bug in is_trivially_copy_constructible which breaks
// std::vector for non-copyable types
#elif(defined(__GNUC__) && __GNUC__ < 8 && !defined(__clang__))
#ifndef TL_GCC_LESS_8_TRIVIALLY_COPY_CONSTRUCTIBLE_MUTEX
#define TL_GCC_LESS_8_TRIVIALLY_COPY_CONSTRUCTIBLE_MUTEX
namespace tl
{
namespace detail
{
template < class T >
struct is_trivially_copy_constructible
: std::is_trivially_copy_constructible< T >
{
};
#ifdef _GLIBCXX_VECTOR
template < class T, class A >
struct is_trivially_copy_constructible< std::vector< T, A > >
: std::is_trivially_copy_constructible< T >
{
};
#endif
} // namespace detail
} // namespace tl
#endif
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
tl::detail::is_trivially_copy_constructible< T >::value
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
std::is_trivially_copy_assignable< T >::value
#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) \
std::is_trivially_destructible< T >::value
#else
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
std::is_trivially_copy_constructible< T >::value
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
std::is_trivially_copy_assignable< T >::value
#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) \
std::is_trivially_destructible< T >::value
#endif
#if __cplusplus > 201103L
#define TL_OPTIONAL_CXX14
#endif
// constexpr implies const in C++11, not C++14
#if(__cplusplus == 201103L || defined(TL_OPTIONAL_MSVC2015) \
|| defined(TL_OPTIONAL_GCC49))
/// \exclude
#define TL_OPTIONAL_11_CONSTEXPR
#else
/// \exclude
#define TL_OPTIONAL_11_CONSTEXPR constexpr
#endif
namespace tl
{
#ifndef TL_MONOSTATE_INPLACE_MUTEX
#define TL_MONOSTATE_INPLACE_MUTEX
/// \brief Used to represent an optional with no data; essentially a bool
class monostate
{
};
/// \brief A tag type to tell optional to construct its value in-place
struct in_place_t
{
explicit in_place_t() = default;
};
/// \brief A tag to tell optional to construct its value in-place
static constexpr in_place_t in_place{};
#endif
template < class T >
class optional;
/// \exclude
namespace detail
{
#ifndef TL_TRAITS_MUTEX
#define TL_TRAITS_MUTEX
// C++14-style aliases for brevity
template < class T >
using remove_const_t = typename std::remove_const< T >::type;
template < class T >
using remove_reference_t = typename std::remove_reference< T >::type;
template < class T >
using decay_t = typename std::decay< T >::type;
template < bool E, class T = void >
using enable_if_t = typename std::enable_if< E, T >::type;
template < bool B, class T, class F >
using conditional_t = typename std::conditional< B, T, F >::type;
// std::conjunction from C++17
template < class... >
struct conjunction : std::true_type
{
};
template < class B >
struct conjunction< B > : B
{
};
template < class B, class... Bs >
struct conjunction< B, Bs... >
: std::conditional< bool(B::value), conjunction< Bs... >, B >::type
{
};
#if defined(_LIBCPP_VERSION) && __cplusplus == 201103L
#define TL_OPTIONAL_LIBCXX_MEM_FN_WORKAROUND
#endif
// In C++11 mode, there's an issue in libc++'s std::mem_fn
// which results in a hard-error when using it in a noexcept expression
// in some cases. This is a check to workaround the common failing case.
#ifdef TL_OPTIONAL_LIBCXX_MEM_FN_WORKAROUND
template < class T >
struct is_pointer_to_non_const_member_func : std::false_type
{
};
template < class T, class Ret, class... Args >
struct is_pointer_to_non_const_member_func< Ret (T::*)(Args...) >
: std::true_type
{
};
template < class T, class Ret, class... Args >
struct is_pointer_to_non_const_member_func< Ret (T::*)(Args...) & >
: std::true_type
{
};
template < class T, class Ret, class... Args >
struct is_pointer_to_non_const_member_func< Ret (T::*)(Args...) && >
: std::true_type
{
};
template < class T, class Ret, class... Args >
struct is_pointer_to_non_const_member_func< Ret (T::*)(Args...) volatile >
: std::true_type
{
};
template < class T, class Ret, class... Args >
struct is_pointer_to_non_const_member_func< Ret (T::*)(Args...) volatile & >
: std::true_type
{
};
template < class T, class Ret, class... Args >
struct is_pointer_to_non_const_member_func< Ret (T::*)(
Args...) volatile && > : std::true_type
{
};
template < class T >
struct is_const_or_const_ref : std::false_type
{
};
template < class T >
struct is_const_or_const_ref< T const & > : std::true_type
{
};
template < class T >
struct is_const_or_const_ref< T const > : std::true_type
{
};
#endif
// std::invoke from C++17
// https://stackoverflow.com/questions/38288042/c11-14-invoke-workaround
template <
typename Fn, typename... Args,
#ifdef TL_OPTIONAL_LIBCXX_MEM_FN_WORKAROUND
typename =
enable_if_t< !(is_pointer_to_non_const_member_func< Fn >::value
&& is_const_or_const_ref< Args... >::value) >,
#endif
typename =
enable_if_t< std::is_member_pointer< decay_t< Fn > >::value >,
int = 0 >
constexpr auto
invoke(Fn &&f, Args &&... args) noexcept(
noexcept(std::mem_fn(f)(std::forward< Args >(args)...)))
-> decltype(std::mem_fn(f)(std::forward< Args >(args)...))
{
return std::mem_fn(f)(std::forward< Args >(args)...);
}
template < typename Fn, typename... Args,
typename = enable_if_t<
!std::is_member_pointer< decay_t< Fn > >::value > >
constexpr auto
invoke(Fn &&f, Args &&... args) noexcept(
noexcept(std::forward< Fn >(f)(std::forward< Args >(args)...)))
-> decltype(std::forward< Fn >(f)(std::forward< Args >(args)...))
{
return std::forward< Fn >(f)(std::forward< Args >(args)...);
}
// std::invoke_result from C++17
template < class F, class, class... Us >
struct invoke_result_impl;
template < class F, class... Us >
struct invoke_result_impl< F,
decltype(detail::invoke(std::declval< F >(),
std::declval< Us >()...),
void()),
Us... >
{
using type = decltype(
detail::invoke(std::declval< F >(), std::declval< Us >()...));
};
template < class F, class... Us >
using invoke_result = invoke_result_impl< F, void, Us... >;
template < class F, class... Us >
using invoke_result_t = typename invoke_result< F, Us... >::type;
#endif
// std::void_t from C++17
template < class... >
struct voider
{
using type = void;
};
template < class... Ts >
using void_t = typename voider< Ts... >::type;
// Trait for checking if a type is a tl::optional
template < class T >
struct is_optional_impl : std::false_type
{
};
template < class T >
struct is_optional_impl< optional< T > > : std::true_type
{
};
template < class T >
using is_optional = is_optional_impl< decay_t< T > >;
// Change void to tl::monostate
template < class U >
using fixup_void = conditional_t< std::is_void< U >::value, monostate, U >;
template < class F, class U, class = invoke_result_t< F, U > >
using get_map_return = optional< fixup_void< invoke_result_t< F, U > > >;
// Check if invoking F for some Us returns void
template < class F, class = void, class... U >
struct returns_void_impl;
template < class F, class... U >
struct returns_void_impl< F, void_t< invoke_result_t< F, U... > >, U... >
: std::is_void< invoke_result_t< F, U... > >
{
};
template < class F, class... U >
using returns_void = returns_void_impl< F, void, U... >;
template < class T, class... U >
using enable_if_ret_void = enable_if_t< returns_void< T &&, U... >::value >;
template < class T, class... U >
using disable_if_ret_void =
enable_if_t< !returns_void< T &&, U... >::value >;
template < class T, class U >
using enable_forward_value = detail::enable_if_t<
std::is_constructible< T, U && >::value
&& !std::is_same< detail::decay_t< U >, in_place_t >::value
&& !std::is_same< optional< T >, detail::decay_t< U > >::value >;
template < class T, class U, class Other >
using enable_from_other = detail::enable_if_t<
std::is_constructible< T, Other >::value
&& !std::is_constructible< T, optional< U > & >::value
&& !std::is_constructible< T, optional< U > && >::value
&& !std::is_constructible< T, const optional< U > & >::value
&& !std::is_constructible< T, const optional< U > && >::value
&& !std::is_convertible< optional< U > &, T >::value
&& !std::is_convertible< optional< U > &&, T >::value
&& !std::is_convertible< const optional< U > &, T >::value
&& !std::is_convertible< const optional< U > &&, T >::value >;
template < class T, class U >
using enable_assign_forward = detail::enable_if_t<
!std::is_same< optional< T >, detail::decay_t< U > >::value
&& !detail::conjunction<
std::is_scalar< T >,
std::is_same< T, detail::decay_t< U > > >::value
&& std::is_constructible< T, U >::value
&& std::is_assignable< T &, U >::value >;
template < class T, class U, class Other >
using enable_assign_from_other = detail::enable_if_t<
std::is_constructible< T, Other >::value
&& std::is_assignable< T &, Other >::value
&& !std::is_constructible< T, optional< U > & >::value
&& !std::is_constructible< T, optional< U > && >::value
&& !std::is_constructible< T, const optional< U > & >::value
&& !std::is_constructible< T, const optional< U > && >::value
&& !std::is_convertible< optional< U > &, T >::value
&& !std::is_convertible< optional< U > &&, T >::value
&& !std::is_convertible< const optional< U > &, T >::value
&& !std::is_convertible< const optional< U > &&, T >::value
&& !std::is_assignable< T &, optional< U > & >::value
&& !std::is_assignable< T &, optional< U > && >::value
&& !std::is_assignable< T &, const optional< U > & >::value
&& !std::is_assignable< T &, const optional< U > && >::value >;
#ifdef _MSC_VER
// TODO make a version which works with MSVC
template < class T, class U = T >
struct is_swappable : std::true_type
{
};
template < class T, class U = T >
struct is_nothrow_swappable : std::true_type
{
};
#else
// https://stackoverflow.com/questions/26744589/what-is-a-proper-way-to-implement-is-swappable-to-test-for-the-swappable-concept
namespace swap_adl_tests
{
// if swap ADL finds this then it would call std::swap otherwise (same
// signature)
struct tag
{
};
template < class T >
tag
swap(T &, T &);
template < class T, std::size_t N >
tag swap(T (&a)[N], T (&b)[N]);
// helper functions to test if an unqualified swap is possible, and if it
// becomes std::swap
template < class, class >
std::false_type
can_swap(...) noexcept(false);
template < class T, class U,
class = decltype(swap(std::declval< T & >(),
std::declval< U & >())) >
std::true_type
can_swap(int) noexcept(noexcept(swap(std::declval< T & >(),
std::declval< U & >())));
template < class, class >
std::false_type
uses_std(...);
template < class T, class U >
std::is_same<
decltype(swap(std::declval< T & >(), std::declval< U & >())), tag >
uses_std(int);
template < class T >
struct is_std_swap_noexcept
: std::integral_constant<
bool,
std::is_nothrow_move_constructible< T >::value
&& std::is_nothrow_move_assignable< T >::value >
{
};
template < class T, std::size_t N >
struct is_std_swap_noexcept< T[N] > : is_std_swap_noexcept< T >
{
};
template < class T, class U >
struct is_adl_swap_noexcept
: std::integral_constant< bool, noexcept(can_swap< T, U >(0)) >
{
};
} // namespace swap_adl_tests
template < class T, class U = T >
struct is_swappable
: std::integral_constant<
bool,
decltype(detail::swap_adl_tests::can_swap< T, U >(0))::value
&& (!decltype(
detail::swap_adl_tests::uses_std< T, U >(0))::value
|| (std::is_move_assignable< T >::value
&& std::is_move_constructible< T >::value)) >
{
};
template < class T, std::size_t N >
struct is_swappable< T[N], T[N] >
: std::integral_constant<
bool,
decltype(detail::swap_adl_tests::can_swap< T[N], T[N] >(0))::value
&& (!decltype(detail::swap_adl_tests::uses_std< T[N], T[N] >(
0))::value
|| is_swappable< T, T >::value) >
{
};
template < class T, class U = T >
struct is_nothrow_swappable
: std::integral_constant<
bool,
is_swappable< T, U >::value
&& ((decltype(detail::swap_adl_tests::uses_std< T, U >(
0))::value &&detail::swap_adl_tests::
is_std_swap_noexcept< T >::value)
|| (!decltype(detail::swap_adl_tests::uses_std< T, U >(
0))::value &&detail::swap_adl_tests::
is_adl_swap_noexcept< T, U >::value)) >
{
};
#endif
// The storage base manages the actual storage, and correctly propagates
// trivial destruction from T. This case is for when T is not trivially
// destructible.
template < class T, bool = ::std::is_trivially_destructible< T >::value >
struct optional_storage_base
{
TL_OPTIONAL_11_CONSTEXPR
optional_storage_base() noexcept : m_dummy(), m_has_value(false)
{
}
template < class... U >
TL_OPTIONAL_11_CONSTEXPR
optional_storage_base(in_place_t, U &&... u)
: m_value(std::forward< U >(u)...), m_has_value(true)
{
}
~optional_storage_base()
{
if(m_has_value)
{
m_value.~T();
m_has_value = false;
}
}
struct dummy
{
};
union {
dummy m_dummy;
T m_value;
};
bool m_has_value;
};
// This case is for when T is trivially destructible.
template < class T >
struct optional_storage_base< T, true >
{
TL_OPTIONAL_11_CONSTEXPR
optional_storage_base() noexcept : m_dummy(), m_has_value(false)
{
}
template < class... U >
TL_OPTIONAL_11_CONSTEXPR
optional_storage_base(in_place_t, U &&... u)
: m_value(std::forward< U >(u)...), m_has_value(true)
{
}
// No destructor, so this class is trivially destructible
struct dummy
{
};
union {
dummy m_dummy;
T m_value;
};
bool m_has_value = false;
};
// This base class provides some handy member functions which can be used in
// further derived classes
template < class T >
struct optional_operations_base : optional_storage_base< T >
{
using optional_storage_base< T >::optional_storage_base;
void
hard_reset() noexcept
{
get().~T();
this->m_has_value = false;
}
template < class... Args >
void
construct(Args &&... args) noexcept
{
new(std::addressof(this->m_value)) T(std::forward< Args >(args)...);
this->m_has_value = true;
}
template < class Opt >
void
assign(Opt &&rhs)
{
if(this->has_value())
{
if(rhs.has_value())
{
this->m_value = std::forward< Opt >(rhs).get();
}
else
{
this->m_value.~T();
this->m_has_value = false;
}
}
else if(rhs.has_value())
{
construct(std::forward< Opt >(rhs).get());
}
}
bool
has_value() const
{
return this->m_has_value;
}
TL_OPTIONAL_11_CONSTEXPR T &
get() &
{
return this->m_value;
}
TL_OPTIONAL_11_CONSTEXPR const T &
get() const &
{
return this->m_value;
}
TL_OPTIONAL_11_CONSTEXPR T &&
get() &&
{
return std::move(this->m_value);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
constexpr const T &&
get() const &&
{
return std::move(this->m_value);
}
#endif
};
// This class manages conditionally having a trivial copy constructor
// This specialization is for when T is trivially copy constructible
template < class T, bool = TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) >
struct optional_copy_base : optional_operations_base< T >
{
using optional_operations_base< T >::optional_operations_base;
};
// This specialization is for when T is not trivially copy constructible
template < class T >
struct optional_copy_base< T, false > : optional_operations_base< T >
{
using optional_operations_base< T >::optional_operations_base;
optional_copy_base() = default;
optional_copy_base(const optional_copy_base &rhs)
{
if(rhs.has_value())
{
this->construct(rhs.get());
}
else
{
this->m_has_value = false;
}
}
optional_copy_base(optional_copy_base &&rhs) = default;
optional_copy_base &
operator=(const optional_copy_base &rhs) = default;
optional_copy_base &
operator=(optional_copy_base &&rhs) = default;
};
// This class manages conditionally having a trivial move constructor
// Unfortunately there's no way to achieve this in GCC < 5 AFAIK, since it
// doesn't implement an analogue to std::is_trivially_move_constructible. We
// have to make do with a non-trivial move constructor even if T is trivially
// move constructible
#ifndef TL_OPTIONAL_GCC49
template < class T,
bool = std::is_trivially_move_constructible< T >::value >
struct optional_move_base : optional_copy_base< T >
{
using optional_copy_base< T >::optional_copy_base;
};
#else
template < class T, bool = false >
struct optional_move_base;
#endif
template < class T >
struct optional_move_base< T, false > : optional_copy_base< T >
{
using optional_copy_base< T >::optional_copy_base;
optional_move_base() = default;
optional_move_base(const optional_move_base &rhs) = default;
optional_move_base(optional_move_base &&rhs) noexcept(
std::is_nothrow_move_constructible< T >::value)
{
if(rhs.has_value())
{
this->construct(std::move(rhs.get()));
}
else
{
this->m_has_value = false;
}
}
optional_move_base &
operator=(const optional_move_base &rhs) = default;
optional_move_base &
operator=(optional_move_base &&rhs) = default;
};
// This class manages conditionally having a trivial copy assignment
// operator
template < class T,
bool = TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T)
&& TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T)
&& TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) >
struct optional_copy_assign_base : optional_move_base< T >
{
using optional_move_base< T >::optional_move_base;
};
template < class T >
struct optional_copy_assign_base< T, false > : optional_move_base< T >
{
using optional_move_base< T >::optional_move_base;
optional_copy_assign_base() = default;
optional_copy_assign_base(const optional_copy_assign_base &rhs) = default;
optional_copy_assign_base(optional_copy_assign_base &&rhs) = default;
optional_copy_assign_base &
operator=(const optional_copy_assign_base &rhs)
{
this->assign(rhs);
return *this;
}
optional_copy_assign_base &
operator=(optional_copy_assign_base &&rhs) = default;
};
// This class manages conditionally having a trivial move assignment operator
// Unfortunately there's no way to achieve this in GCC < 5 AFAIK, since it
// doesn't implement an analogue to std::is_trivially_move_assignable. We have
// to make do with a non-trivial move assignment operator even if T is trivially
// move assignable
#ifndef TL_OPTIONAL_GCC49
template < class T,
bool = std::is_trivially_destructible< T >::value
&&std::is_trivially_move_constructible< T >::value
&&std::is_trivially_move_assignable< T >::value >
struct optional_move_assign_base : optional_copy_assign_base< T >
{
using optional_copy_assign_base< T >::optional_copy_assign_base;
};
#else
template < class T, bool = false >
struct optional_move_assign_base;
#endif
template < class T >
struct optional_move_assign_base< T, false >
: optional_copy_assign_base< T >
{
using optional_copy_assign_base< T >::optional_copy_assign_base;
optional_move_assign_base() = default;
optional_move_assign_base(const optional_move_assign_base &rhs) = default;
optional_move_assign_base(optional_move_assign_base &&rhs) = default;
optional_move_assign_base &
operator=(const optional_move_assign_base &rhs) = default;
optional_move_assign_base &
operator=(optional_move_assign_base &&rhs) noexcept(
std::is_nothrow_move_constructible< T >::value
&&std::is_nothrow_move_assignable< T >::value)
{
this->assign(std::move(rhs));
return *this;
}
};
// optional_delete_ctor_base will conditionally delete copy and move
// constructors depending on whether T is copy/move constructible
template < class T,
bool EnableCopy = std::is_copy_constructible< T >::value,
bool EnableMove = std::is_move_constructible< T >::value >
struct optional_delete_ctor_base
{
optional_delete_ctor_base() = default;
optional_delete_ctor_base(const optional_delete_ctor_base &) = default;
optional_delete_ctor_base(optional_delete_ctor_base &&) noexcept =
default;
optional_delete_ctor_base &
operator=(const optional_delete_ctor_base &) = default;
optional_delete_ctor_base &
operator=(optional_delete_ctor_base &&) noexcept = default;
};
template < class T >
struct optional_delete_ctor_base< T, true, false >
{
optional_delete_ctor_base() = default;
optional_delete_ctor_base(const optional_delete_ctor_base &) = default;
optional_delete_ctor_base(optional_delete_ctor_base &&) noexcept = delete;
optional_delete_ctor_base &
operator=(const optional_delete_ctor_base &) = default;
optional_delete_ctor_base &
operator=(optional_delete_ctor_base &&) noexcept = default;
};
template < class T >
struct optional_delete_ctor_base< T, false, true >
{
optional_delete_ctor_base() = default;
optional_delete_ctor_base(const optional_delete_ctor_base &) = delete;
optional_delete_ctor_base(optional_delete_ctor_base &&) noexcept =
default;
optional_delete_ctor_base &
operator=(const optional_delete_ctor_base &) = default;
optional_delete_ctor_base &
operator=(optional_delete_ctor_base &&) noexcept = default;
};
template < class T >
struct optional_delete_ctor_base< T, false, false >
{
optional_delete_ctor_base() = default;
optional_delete_ctor_base(const optional_delete_ctor_base &) = delete;
optional_delete_ctor_base(optional_delete_ctor_base &&) noexcept = delete;
optional_delete_ctor_base &
operator=(const optional_delete_ctor_base &) = default;
optional_delete_ctor_base &
operator=(optional_delete_ctor_base &&) noexcept = default;
};
// optional_delete_assign_base will conditionally delete copy and move
// constructors depending on whether T is copy/move constructible +
// assignable
template < class T,
bool EnableCopy = (std::is_copy_constructible< T >::value
&& std::is_copy_assignable< T >::value),
bool EnableMove = (std::is_move_constructible< T >::value
&& std::is_move_assignable< T >::value) >
struct optional_delete_assign_base
{
optional_delete_assign_base() = default;
optional_delete_assign_base(const optional_delete_assign_base &) =
default;
optional_delete_assign_base(optional_delete_assign_base &&) noexcept =
default;
optional_delete_assign_base &
operator=(const optional_delete_assign_base &) = default;
optional_delete_assign_base &
operator=(optional_delete_assign_base &&) noexcept = default;
};
template < class T >
struct optional_delete_assign_base< T, true, false >
{
optional_delete_assign_base() = default;
optional_delete_assign_base(const optional_delete_assign_base &) =
default;
optional_delete_assign_base(optional_delete_assign_base &&) noexcept =
default;
optional_delete_assign_base &
operator=(const optional_delete_assign_base &) = default;
optional_delete_assign_base &
operator=(optional_delete_assign_base &&) noexcept = delete;
};
template < class T >
struct optional_delete_assign_base< T, false, true >
{
optional_delete_assign_base() = default;
optional_delete_assign_base(const optional_delete_assign_base &) =
default;
optional_delete_assign_base(optional_delete_assign_base &&) noexcept =
default;
optional_delete_assign_base &
operator=(const optional_delete_assign_base &) = delete;
optional_delete_assign_base &
operator=(optional_delete_assign_base &&) noexcept = default;
};
template < class T >
struct optional_delete_assign_base< T, false, false >
{
optional_delete_assign_base() = default;
optional_delete_assign_base(const optional_delete_assign_base &) =
default;
optional_delete_assign_base(optional_delete_assign_base &&) noexcept =
default;
optional_delete_assign_base &
operator=(const optional_delete_assign_base &) = delete;
optional_delete_assign_base &
operator=(optional_delete_assign_base &&) noexcept = delete;
};
} // namespace detail
/// \brief A tag type to represent an empty optional
struct nullopt_t
{
struct do_not_use
{
};
constexpr explicit nullopt_t(do_not_use, do_not_use) noexcept
{
}
};
/// \brief Represents an empty optional
/// \synopsis static constexpr nullopt_t nullopt;
///
/// *Examples*:
/// ```
/// tl::optional<int> a = tl::nullopt;
/// void foo (tl::optional<int>);
/// foo(tl::nullopt); //pass an empty optional
/// ```
static constexpr nullopt_t nullopt{nullopt_t::do_not_use{},
nullopt_t::do_not_use{}};
class bad_optional_access : public std::exception
{
public:
bad_optional_access() = default;
const char *
what() const noexcept
{
return "Optional has no value";
}
};
/// An optional object is an object that contains the storage for another
/// object and manages the lifetime of this contained object, if any. The
/// contained object may be initialized after the optional object has been
/// initialized, and may be destroyed before the optional object has been
/// destroyed. The initialization state of the contained object is tracked by
/// the optional object.
template < class T >
class optional : private detail::optional_move_assign_base< T >,
private detail::optional_delete_ctor_base< T >,
private detail::optional_delete_assign_base< T >
{
using base = detail::optional_move_assign_base< T >;
static_assert(!std::is_same< T, in_place_t >::value,
"instantiation of optional with in_place_t is ill-formed");
static_assert(!std::is_same< detail::decay_t< T >, nullopt_t >::value,
"instantiation of optional with nullopt_t is ill-formed");
public:
// The different versions for C++14 and 11 are needed because deduced return
// types are not SFINAE-safe. This provides better support for things like
// generic lambdas. C.f.
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0826r0.html
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) \
&& !defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
/// \group and_then
/// Carries out some operation which returns an optional on the stored
/// object if there is one. \requires `std::invoke(std::forward<F>(f),
/// value())` returns a `std::optional<U>` for some `U`. \returns Let `U` be
/// the result of `std::invoke(std::forward<F>(f), value())`. Returns a
/// `std::optional<U>`. The return value is empty if `*this` is empty,
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
/// is returned.
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
template < class F >
TL_OPTIONAL_11_CONSTEXPR auto
and_then(F &&f) &
{
using result = detail::invoke_result_t< F, T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
template < class F >
TL_OPTIONAL_11_CONSTEXPR auto
and_then(F &&f) &&
{
using result = detail::invoke_result_t< F, T && >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: result(nullopt);
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
template < class F >
constexpr auto
and_then(F &&f) const &
{
using result = detail::invoke_result_t< F, const T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
template < class F >
constexpr auto
and_then(F &&f) const &&
{
using result = detail::invoke_result_t< F, const T && >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: result(nullopt);
}
#endif
#else
/// \group and_then
/// Carries out some operation which returns an optional on the stored
/// object if there is one. \requires `std::invoke(std::forward<F>(f),
/// value())` returns a `std::optional<U>` for some `U`.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. Returns a `std::optional<U>`. The return value is empty if
/// `*this` is empty, otherwise the return value of
/// `std::invoke(std::forward<F>(f), value())` is returned.
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
template < class F >
TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t< F, T & >
and_then(F &&f) &
{
using result = detail::invoke_result_t< F, T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
template < class F >
TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t< F, T && >
and_then(F &&f) &&
{
using result = detail::invoke_result_t< F, T && >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: result(nullopt);
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
template < class F >
constexpr detail::invoke_result_t< F, const T & >
and_then(F &&f) const &
{
using result = detail::invoke_result_t< F, const T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
template < class F >
constexpr detail::invoke_result_t< F, const T && >
and_then(F &&f) const &&
{
using result = detail::invoke_result_t< F, const T && >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: result(nullopt);
}
#endif
#endif
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) \
&& !defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
/// \brief Carries out some operation on the stored object if there is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. Returns a `std::optional<U>`. The return value is empty if
/// `*this` is empty, otherwise an `optional<U>` is constructed from the
/// return value of `std::invoke(std::forward<F>(f), value())` and is
/// returned.
///
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) &;
template < class F >
TL_OPTIONAL_11_CONSTEXPR auto
map(F &&f) &
{
return optional_map_impl(*this, std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) &&;
template < class F >
TL_OPTIONAL_11_CONSTEXPR auto
map(F &&f) &&
{
return optional_map_impl(std::move(*this), std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) const&;
template < class F >
constexpr auto
map(F &&f) const &
{
return optional_map_impl(*this, std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) const&&;
template < class F >
constexpr auto
map(F &&f) const &&
{
return optional_map_impl(std::move(*this), std::forward< F >(f));
}
#else
/// \brief Carries out some operation on the stored object if there is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. Returns a `std::optional<U>`. The return value is empty if
/// `*this` is empty, otherwise an `optional<U>` is constructed from the
/// return value of `std::invoke(std::forward<F>(f), value())` and is
/// returned.
///
/// \group map
/// \synopsis template <class F> auto map(F &&f) &;
template < class F >
TL_OPTIONAL_11_CONSTEXPR decltype(
optional_map_impl(std::declval< optional & >(), std::declval< F && >()))
map(F &&f) &
{
return optional_map_impl(*this, std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> auto map(F &&f) &&;
template < class F >
TL_OPTIONAL_11_CONSTEXPR decltype(optional_map_impl(
std::declval< optional && >(), std::declval< F && >()))
map(F &&f) &&
{
return optional_map_impl(std::move(*this), std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> auto map(F &&f) const&;
template < class F >
constexpr decltype(optional_map_impl(std::declval< const optional & >(),
std::declval< F && >()))
map(F &&f) const &
{
return optional_map_impl(*this, std::forward< F >(f));
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group map
/// \synopsis template <class F> auto map(F &&f) const&&;
template < class F >
constexpr decltype(optional_map_impl(std::declval< const optional && >(),
std::declval< F && >()))
map(F &&f) const &&
{
return optional_map_impl(std::move(*this), std::forward< F >(f));
}
#endif
#endif
/// \brief Calls `f` if the optional is empty
/// \requires `std::invoke_result_t<F>` must be void or convertible to
/// `optional<T>`.
/// \effects If `*this` has a value, returns `*this`.
/// Otherwise, if `f` returns `void`, calls `std::forward<F>(f)` and returns
/// `std::nullopt`. Otherwise, returns `std::forward<F>(f)()`.
///
/// \group or_else
/// \synopsis template <class F> optional<T> or_else (F &&f) &;
template < class F, detail::enable_if_ret_void< F > * = nullptr >
optional< T > TL_OPTIONAL_11_CONSTEXPR
or_else(F &&f) &
{
if(has_value())
return *this;
std::forward< F >(f)();
return nullopt;
}
/// \exclude
template < class F, detail::disable_if_ret_void< F > * = nullptr >
optional< T > TL_OPTIONAL_11_CONSTEXPR
or_else(F &&f) &
{
return has_value() ? *this : std::forward< F >(f)();
}
/// \group or_else
/// \synopsis template <class F> optional<T> or_else (F &&f) &&;
template < class F, detail::enable_if_ret_void< F > * = nullptr >
optional< T >
or_else(F &&f) &&
{
if(has_value())
return std::move(*this);
std::forward< F >(f)();
return nullopt;
}
/// \exclude
template < class F, detail::disable_if_ret_void< F > * = nullptr >
optional< T > TL_OPTIONAL_11_CONSTEXPR
or_else(F &&f) &&
{
return has_value() ? std::move(*this) : std::forward< F >(f)();
}
/// \group or_else
/// \synopsis template <class F> optional<T> or_else (F &&f) const &;
template < class F, detail::enable_if_ret_void< F > * = nullptr >
optional< T >
or_else(F &&f) const &
{
if(has_value())
return *this;
std::forward< F >(f)();
return nullopt;
}
/// \exclude
template < class F, detail::disable_if_ret_void< F > * = nullptr >
optional< T > TL_OPTIONAL_11_CONSTEXPR
or_else(F &&f) const &
{
return has_value() ? *this : std::forward< F >(f)();
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \exclude
template < class F, detail::enable_if_ret_void< F > * = nullptr >
optional< T >
or_else(F &&f) const &&
{
if(has_value())
return std::move(*this);
std::forward< F >(f)();
return nullopt;
}
/// \exclude
template < class F, detail::disable_if_ret_void< F > * = nullptr >
optional< T >
or_else(F &&f) const &&
{
return has_value() ? std::move(*this) : std::forward< F >(f)();
}
#endif
/// \brief Maps the stored value with `f` if there is one, otherwise returns
/// `u`.
///
/// \details If there is a value stored, then `f` is called with `**this`
/// and the value is returned. Otherwise `u` is returned.
///
/// \group map_or
template < class F, class U >
U
map_or(F &&f, U &&u) &
{
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: std::forward< U >(u);
}
/// \group map_or
template < class F, class U >
U
map_or(F &&f, U &&u) &&
{
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: std::forward< U >(u);
}
/// \group map_or
template < class F, class U >
U
map_or(F &&f, U &&u) const &
{
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: std::forward< U >(u);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group map_or
template < class F, class U >
U
map_or(F &&f, U &&u) const &&
{
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: std::forward< U >(u);
}
#endif
/// \brief Maps the stored value with `f` if there is one, otherwise calls
/// `u` and returns the result.
///
/// \details If there is a value stored, then `f` is
/// called with `**this` and the value is returned. Otherwise
/// `std::forward<U>(u)()` is returned.
///
/// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u) &;
template < class F, class U >
detail::invoke_result_t< U >
map_or_else(F &&f, U &&u) &
{
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: std::forward< U >(u)();
}
/// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
/// &&;
template < class F, class U >
detail::invoke_result_t< U >
map_or_else(F &&f, U &&u) &&
{
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: std::forward< U >(u)();
}
/// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
/// const &;
template < class F, class U >
detail::invoke_result_t< U >
map_or_else(F &&f, U &&u) const &
{
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: std::forward< U >(u)();
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
/// const &&;
template < class F, class U >
detail::invoke_result_t< U >
map_or_else(F &&f, U &&u) const &&
{
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: std::forward< U >(u)();
}
#endif
/// \returns `u` if `*this` has a value, otherwise an empty optional.
template < class U >
constexpr optional< typename std::decay< U >::type >
conjunction(U &&u) const
{
using result = optional< detail::decay_t< U > >;
return has_value() ? result{u} : result{nullopt};
}
/// \returns `rhs` if `*this` is empty, otherwise the current value.
/// \group disjunction
TL_OPTIONAL_11_CONSTEXPR optional
disjunction(const optional &rhs) &
{
return has_value() ? *this : rhs;
}
/// \group disjunction
constexpr optional
disjunction(const optional &rhs) const &
{
return has_value() ? *this : rhs;
}
/// \group disjunction
TL_OPTIONAL_11_CONSTEXPR optional
disjunction(const optional &rhs) &&
{
return has_value() ? std::move(*this) : rhs;
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group disjunction
constexpr optional
disjunction(const optional &rhs) const &&
{
return has_value() ? std::move(*this) : rhs;
}
#endif
/// \group disjunction
TL_OPTIONAL_11_CONSTEXPR optional
disjunction(optional &&rhs) &
{
return has_value() ? *this : std::move(rhs);
}
/// \group disjunction
constexpr optional
disjunction(optional &&rhs) const &
{
return has_value() ? *this : std::move(rhs);
}
/// \group disjunction
TL_OPTIONAL_11_CONSTEXPR optional
disjunction(optional &&rhs) &&
{
return has_value() ? std::move(*this) : std::move(rhs);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group disjunction
constexpr optional
disjunction(optional &&rhs) const &&
{
return has_value() ? std::move(*this) : std::move(rhs);
}
#endif
/// Takes the value out of the optional, leaving it empty
/// \group take
optional
take() &
{
optional ret = *this;
reset();
return ret;
}
/// \group take
optional
take() const &
{
optional ret = *this;
reset();
return ret;
}
/// \group take
optional
take() &&
{
optional ret = std::move(*this);
reset();
return ret;
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group take
optional
take() const &&
{
optional ret = std::move(*this);
reset();
return ret;
}
#endif
using value_type = T;
/// Constructs an optional that does not contain a value.
/// \group ctor_empty
constexpr optional() noexcept = default;
/// \group ctor_empty
constexpr optional(nullopt_t) noexcept
{
}
/// Copy constructor
///
/// If `rhs` contains a value, the stored value is direct-initialized with
/// it. Otherwise, the constructed optional is empty.
TL_OPTIONAL_11_CONSTEXPR
optional(const optional &rhs) = default;
/// Move constructor
///
/// If `rhs` contains a value, the stored value is direct-initialized with
/// it. Otherwise, the constructed optional is empty.
TL_OPTIONAL_11_CONSTEXPR
optional(optional &&rhs) = default;
/// Constructs the stored value in-place using the given arguments.
/// \group in_place
/// \synopsis template <class... Args> constexpr explicit
/// optional(in_place_t, Args&&... args);
template < class... Args >
constexpr explicit optional(
detail::enable_if_t< std::is_constructible< T, Args... >::value,
in_place_t >,
Args &&... args)
: base(in_place, std::forward< Args >(args)...)
{
}
/// \group in_place
/// \synopsis template <class U, class... Args>\nconstexpr explicit
/// optional(in_place_t, std::initializer_list<U>&, Args&&... args);
template < class U, class... Args >
TL_OPTIONAL_11_CONSTEXPR explicit optional(
detail::enable_if_t<
std::is_constructible< T, std::initializer_list< U > &,
Args &&... >::value,
in_place_t >,
std::initializer_list< U > il, Args &&... args)
{
this->construct(il, std::forward< Args >(args)...);
}
/// Constructs the stored value with `u`.
/// \synopsis template <class U=T> constexpr optional(U &&u);
template < class U = T,
detail::enable_if_t< std::is_convertible< U &&, T >::value > * =
nullptr,
detail::enable_forward_value< T, U > * = nullptr >
constexpr optional(U &&u) : base(in_place, std::forward< U >(u))
{
}
/// \exclude
template < class U = T,
detail::enable_if_t< !std::is_convertible< U &&, T >::value > * =
nullptr,
detail::enable_forward_value< T, U > * = nullptr >
constexpr explicit optional(U &&u) : base(in_place, std::forward< U >(u))
{
}
/// Converting copy constructor.
/// \synopsis template <class U> optional(const optional<U> &rhs);
template < class U,
detail::enable_from_other< T, U, const U & > * = nullptr,
detail::enable_if_t< std::is_convertible< const U &, T >::value >
* = nullptr >
optional(const optional< U > &rhs)
{
this->construct(*rhs);
}
/// \exclude
template <
class U, detail::enable_from_other< T, U, const U & > * = nullptr,
detail::enable_if_t< !std::is_convertible< const U &, T >::value > * =
nullptr >
explicit optional(const optional< U > &rhs)
{
this->construct(*rhs);
}
/// Converting move constructor.
/// \synopsis template <class U> optional(optional<U> &&rhs);
template < class U, detail::enable_from_other< T, U, U && > * = nullptr,
detail::enable_if_t< std::is_convertible< U &&, T >::value > * =
nullptr >
optional(optional< U > &&rhs)
{
this->construct(std::move(*rhs));
}
/// \exclude
template < class U, detail::enable_from_other< T, U, U && > * = nullptr,
detail::enable_if_t< !std::is_convertible< U &&, T >::value > * =
nullptr >
explicit optional(optional< U > &&rhs)
{
this->construct(std::move(*rhs));
}
/// Destroys the stored value if there is one.
~optional() = default;
/// Assignment to empty.
///
/// Destroys the current value if there is one.
optional &operator=(nullopt_t) noexcept
{
if(has_value())
{
this->m_value.~T();
this->m_has_value = false;
}
return *this;
}
/// Copy assignment.
///
/// Copies the value from `rhs` if there is one. Otherwise resets the stored
/// value in `*this`.
optional &
operator=(const optional &rhs) = default;
/// Move assignment.
///
/// Moves the value from `rhs` if there is one. Otherwise resets the stored
/// value in `*this`.
optional &
operator=(optional &&rhs) = default;
/// Assigns the stored value from `u`, destroying the old value if there was
/// one.
/// \synopsis optional &operator=(U &&u);
template < class U = T, detail::enable_assign_forward< T, U > * = nullptr >
optional &
operator=(U &&u)
{
if(has_value())
{
this->m_value = std::forward< U >(u);
}
else
{
this->construct(std::forward< U >(u));
}
return *this;
}
/// Converting copy assignment operator.
///
/// Copies the value from `rhs` if there is one. Otherwise resets the stored
/// value in `*this`.
/// \synopsis optional &operator=(const optional<U> & rhs);
template < class U,
detail::enable_assign_from_other< T, U, const U & > * = nullptr >
optional &
operator=(const optional< U > &rhs)
{
if(has_value())
{
if(rhs.has_value())
{
this->m_value = *rhs;
}
else
{
this->hard_reset();
}
}
if(rhs.has_value())
{
this->construct(*rhs);
}
return *this;
}
// TODO check exception guarantee
/// Converting move assignment operator.
///
/// Moves the value from `rhs` if there is one. Otherwise resets the stored
/// value in `*this`.
/// \synopsis optional &operator=(optional<U> && rhs);
template < class U,
detail::enable_assign_from_other< T, U, U > * = nullptr >
optional &
operator=(optional< U > &&rhs)
{
if(has_value())
{
if(rhs.has_value())
{
this->m_value = std::move(*rhs);
}
else
{
this->hard_reset();
}
}
if(rhs.has_value())
{
this->construct(std::move(*rhs));
}
return *this;
}
/// Constructs the value in-place, destroying the current one if there is
/// one.
/// \group emplace
template < class... Args >
T &
emplace(Args &&... args)
{
static_assert(std::is_constructible< T, Args &&... >::value,
"T must be constructible with Args");
*this = nullopt;
this->construct(std::forward< Args >(args)...);
return value();
}
/// \group emplace
/// \synopsis template <class U, class... Args>\nT&
/// emplace(std::initializer_list<U> il, Args &&... args);
template < class U, class... Args >
detail::enable_if_t< std::is_constructible< T, std::initializer_list< U > &,
Args &&... >::value,
T & >
emplace(std::initializer_list< U > il, Args &&... args)
{
*this = nullopt;
this->construct(il, std::forward< Args >(args)...);
return value();
}
/// Swaps this optional with the other.
///
/// If neither optionals have a value, nothing happens.
/// If both have a value, the values are swapped.
/// If one has a value, it is moved to the other and the movee is left
/// valueless.
void
swap(optional &rhs) noexcept(std::is_nothrow_move_constructible< T >::value
&&detail::is_nothrow_swappable< T >::value)
{
if(has_value())
{
if(rhs.has_value())
{
using std::swap;
swap(**this, *rhs);
}
else
{
new(std::addressof(rhs.m_value)) T(std::move(this->m_value));
this->m_value.T::~T();
}
}
else if(rhs.has_value())
{
new(std::addressof(this->m_value)) T(std::move(rhs.m_value));
rhs.m_value.T::~T();
}
}
/// \returns a pointer to the stored value
/// \requires a value is stored
/// \group pointer
/// \synopsis constexpr const T *operator->() const;
constexpr const T *operator->() const
{
return std::addressof(this->m_value);
}
/// \group pointer
/// \synopsis constexpr T *operator->();
TL_OPTIONAL_11_CONSTEXPR T *operator->()
{
return std::addressof(this->m_value);
}
/// \returns the stored value
/// \requires a value is stored
/// \group deref
/// \synopsis constexpr T &operator*();
TL_OPTIONAL_11_CONSTEXPR T &operator*() &
{
return this->m_value;
}
/// \group deref
/// \synopsis constexpr const T &operator*() const;
constexpr const T &operator*() const &
{
return this->m_value;
}
/// \exclude
TL_OPTIONAL_11_CONSTEXPR T &&operator*() &&
{
return std::move(this->m_value);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \exclude
constexpr const T &&operator*() const &&
{
return std::move(this->m_value);
}
#endif
/// \returns whether or not the optional has a value
/// \group has_value
constexpr bool
has_value() const noexcept
{
return this->m_has_value;
}
/// \group has_value
constexpr explicit operator bool() const noexcept
{
return this->m_has_value;
}
/// \returns the contained value if there is one, otherwise throws
/// [bad_optional_access]
/// \group value
/// \synopsis constexpr T &value();
TL_OPTIONAL_11_CONSTEXPR T &
value() &
{
if(has_value())
return this->m_value;
throw bad_optional_access();
}
/// \group value
/// \synopsis constexpr const T &value() const;
TL_OPTIONAL_11_CONSTEXPR const T &
value() const &
{
if(has_value())
return this->m_value;
throw bad_optional_access();
}
/// \exclude
TL_OPTIONAL_11_CONSTEXPR T &&
value() &&
{
if(has_value())
return std::move(this->m_value);
throw bad_optional_access();
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \exclude
TL_OPTIONAL_11_CONSTEXPR const T &&
value() const &&
{
if(has_value())
return std::move(this->m_value);
throw bad_optional_access();
}
#endif
/// \returns the stored value if there is one, otherwise returns `u`
/// \group value_or
template < class U >
constexpr T
value_or(U &&u) const &
{
static_assert(std::is_copy_constructible< T >::value
&& std::is_convertible< U &&, T >::value,
"T must be copy constructible and convertible from U");
return has_value() ? **this : static_cast< T >(std::forward< U >(u));
}
/// \group value_or
template < class U >
TL_OPTIONAL_11_CONSTEXPR T
value_or(U &&u) &&
{
static_assert(std::is_move_constructible< T >::value
&& std::is_convertible< U &&, T >::value,
"T must be move constructible and convertible from U");
return has_value() ? **this : static_cast< T >(std::forward< U >(u));
}
/// Destroys the stored value if one exists, making the optional empty
void
reset() noexcept
{
if(has_value())
{
this->m_value.~T();
this->m_has_value = false;
}
}
}; // namespace tl
/// \group relop
/// \brief Compares two optional objects
/// \details If both optionals contain a value, they are compared with `T`s
/// relational operators. Otherwise `lhs` and `rhs` are equal only if they are
/// both empty, and `lhs` is less than `rhs` only if `rhs` is empty and `lhs`
/// is not.
template < class T, class U >
inline constexpr bool
operator==(const optional< T > &lhs, const optional< U > &rhs)
{
return lhs.has_value() == rhs.has_value()
&& (!lhs.has_value() || *lhs == *rhs);
}
/// \group relop
template < class T, class U >
inline constexpr bool
operator!=(const optional< T > &lhs, const optional< U > &rhs)
{
return lhs.has_value() != rhs.has_value()
|| (lhs.has_value() && *lhs != *rhs);
}
/// \group relop
template < class T, class U >
inline constexpr bool
operator<(const optional< T > &lhs, const optional< U > &rhs)
{
return rhs.has_value() && (!lhs.has_value() || *lhs < *rhs);
}
/// \group relop
template < class T, class U >
inline constexpr bool
operator>(const optional< T > &lhs, const optional< U > &rhs)
{
return lhs.has_value() && (!rhs.has_value() || *lhs > *rhs);
}
/// \group relop
template < class T, class U >
inline constexpr bool
operator<=(const optional< T > &lhs, const optional< U > &rhs)
{
return !lhs.has_value() || (rhs.has_value() && *lhs <= *rhs);
}
/// \group relop
template < class T, class U >
inline constexpr bool
operator>=(const optional< T > &lhs, const optional< U > &rhs)
{
return !rhs.has_value() || (lhs.has_value() && *lhs >= *rhs);
}
/// \group relop_nullopt
/// \brief Compares an optional to a `nullopt`
/// \details Equivalent to comparing the optional to an empty optional
template < class T >
inline constexpr bool
operator==(const optional< T > &lhs, nullopt_t) noexcept
{
return !lhs.has_value();
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator==(nullopt_t, const optional< T > &rhs) noexcept
{
return !rhs.has_value();
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator!=(const optional< T > &lhs, nullopt_t) noexcept
{
return lhs.has_value();
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator!=(nullopt_t, const optional< T > &rhs) noexcept
{
return rhs.has_value();
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator<(const optional< T > &, nullopt_t) noexcept
{
return false;
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator<(nullopt_t, const optional< T > &rhs) noexcept
{
return rhs.has_value();
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator<=(const optional< T > &lhs, nullopt_t) noexcept
{
return !lhs.has_value();
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator<=(nullopt_t, const optional< T > &) noexcept
{
return true;
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator>(const optional< T > &lhs, nullopt_t) noexcept
{
return lhs.has_value();
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator>(nullopt_t, const optional< T > &) noexcept
{
return false;
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator>=(const optional< T > &, nullopt_t) noexcept
{
return true;
}
/// \group relop_nullopt
template < class T >
inline constexpr bool
operator>=(nullopt_t, const optional< T > &rhs) noexcept
{
return !rhs.has_value();
}
/// \group relop_t
/// \brief Compares the optional with a value.
/// \details If the optional has a value, it is compared with the other value
/// using `T`s relational operators. Otherwise, the optional is considered
/// less than the value.
template < class T, class U >
inline constexpr bool
operator==(const optional< T > &lhs, const U &rhs)
{
return lhs.has_value() ? *lhs == rhs : false;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator==(const U &lhs, const optional< T > &rhs)
{
return rhs.has_value() ? lhs == *rhs : false;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator!=(const optional< T > &lhs, const U &rhs)
{
return lhs.has_value() ? *lhs != rhs : true;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator!=(const U &lhs, const optional< T > &rhs)
{
return rhs.has_value() ? lhs != *rhs : true;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator<(const optional< T > &lhs, const U &rhs)
{
return lhs.has_value() ? *lhs < rhs : true;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator<(const U &lhs, const optional< T > &rhs)
{
return rhs.has_value() ? lhs < *rhs : false;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator<=(const optional< T > &lhs, const U &rhs)
{
return lhs.has_value() ? *lhs <= rhs : true;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator<=(const U &lhs, const optional< T > &rhs)
{
return rhs.has_value() ? lhs <= *rhs : false;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator>(const optional< T > &lhs, const U &rhs)
{
return lhs.has_value() ? *lhs > rhs : false;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator>(const U &lhs, const optional< T > &rhs)
{
return rhs.has_value() ? lhs > *rhs : true;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator>=(const optional< T > &lhs, const U &rhs)
{
return lhs.has_value() ? *lhs >= rhs : false;
}
/// \group relop_t
template < class T, class U >
inline constexpr bool
operator>=(const U &lhs, const optional< T > &rhs)
{
return rhs.has_value() ? lhs >= *rhs : true;
}
/// \synopsis template <class T>\nvoid swap(optional<T> &lhs, optional<T>
/// &rhs);
template <
class T,
detail::enable_if_t< std::is_move_constructible< T >::value > * = nullptr,
detail::enable_if_t< detail::is_swappable< T >::value > * = nullptr >
void
swap(optional< T > &lhs, optional< T > &rhs) noexcept(noexcept(lhs.swap(rhs)))
{
return lhs.swap(rhs);
}
namespace detail
{
struct i_am_secret
{
};
} // namespace detail
template < class T = detail::i_am_secret, class U,
class Ret = detail::conditional_t<
std::is_same< T, detail::i_am_secret >::value,
detail::decay_t< U >, T > >
inline constexpr optional< Ret >
make_optional(U &&v)
{
return optional< Ret >(std::forward< U >(v));
}
template < class T, class... Args >
inline constexpr optional< T >
make_optional(Args &&... args)
{
return optional< T >(in_place, std::forward< Args >(args)...);
}
template < class T, class U, class... Args >
inline constexpr optional< T >
make_optional(std::initializer_list< U > il, Args &&... args)
{
return optional< T >(in_place, il, std::forward< Args >(args)...);
}
#if __cplusplus >= 201703L
template < class T >
optional(T)->optional< T >;
#endif
/// \exclude
namespace detail
{
#ifdef TL_OPTIONAL_CXX14
template < class Opt, class F,
class Ret = decltype(detail::invoke(std::declval< F >(),
*std::declval< Opt >())),
detail::enable_if_t< !std::is_void< Ret >::value > * = nullptr >
constexpr auto
optional_map_impl(Opt &&opt, F &&f)
{
return opt.has_value()
? detail::invoke(std::forward< F >(f), *std::forward< Opt >(opt))
: optional< Ret >(nullopt);
}
template < class Opt, class F,
class Ret = decltype(detail::invoke(std::declval< F >(),
*std::declval< Opt >())),
detail::enable_if_t< std::is_void< Ret >::value > * = nullptr >
auto
optional_map_impl(Opt &&opt, F &&f)
{
if(opt.has_value())
{
detail::invoke(std::forward< F >(f), *std::forward< Opt >(opt));
return make_optional(monostate{});
}
return optional< monostate >(nullopt);
}
#else
template < class Opt, class F,
class Ret = decltype(detail::invoke(std::declval< F >(),
*std::declval< Opt >())),
detail::enable_if_t< !std::is_void< Ret >::value > * = nullptr >
constexpr auto
optional_map_impl(Opt &&opt, F &&f) -> optional< Ret >
{
return opt.has_value()
? detail::invoke(std::forward< F >(f), *std::forward< Opt >(opt))
: optional< Ret >(nullopt);
}
template < class Opt, class F,
class Ret = decltype(detail::invoke(std::declval< F >(),
*std::declval< Opt >())),
detail::enable_if_t< std::is_void< Ret >::value > * = nullptr >
auto
optional_map_impl(Opt &&opt, F &&f) -> optional< monostate >
{
if(opt.has_value())
{
detail::invoke(std::forward< F >(f), *std::forward< Opt >(opt));
return monostate{};
}
return nullopt;
}
#endif
} // namespace detail
/// Specialization for when `T` is a reference. `optional<T&>` acts similarly
/// to a `T*`, but provides more operations and shows intent more clearly.
///
/// *Examples*:
///
/// ```
/// int i = 42;
/// tl::optional<int&> o = i;
/// *o == 42; //true
/// i = 12;
/// *o = 12; //true
/// &*o == &i; //true
/// ```
///
/// Assignment has rebind semantics rather than assign-through semantics:
///
/// ```
/// int j = 8;
/// o = j;
///
/// &*o == &j; //true
/// ```
template < class T >
class optional< T & >
{
public:
// The different versions for C++14 and 11 are needed because deduced return
// types are not SFINAE-safe. This provides better support for things like
// generic lambdas. C.f.
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0826r0.html
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) \
&& !defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
/// \group and_then
/// Carries out some operation which returns an optional on the stored
/// object if there is one. \requires `std::invoke(std::forward<F>(f),
/// value())` returns a `std::optional<U>` for some `U`. \returns Let `U` be
/// the result of `std::invoke(std::forward<F>(f), value())`. Returns a
/// `std::optional<U>`. The return value is empty if `*this` is empty,
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
/// is returned.
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
template < class F >
TL_OPTIONAL_11_CONSTEXPR auto
and_then(F &&f) &
{
using result = detail::invoke_result_t< F, T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
template < class F >
TL_OPTIONAL_11_CONSTEXPR auto
and_then(F &&f) &&
{
using result = detail::invoke_result_t< F, T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
template < class F >
constexpr auto
and_then(F &&f) const &
{
using result = detail::invoke_result_t< F, const T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
template < class F >
constexpr auto
and_then(F &&f) const &&
{
using result = detail::invoke_result_t< F, const T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
#endif
#else
/// \group and_then
/// Carries out some operation which returns an optional on the stored
/// object if there is one. \requires `std::invoke(std::forward<F>(f),
/// value())` returns a `std::optional<U>` for some `U`. \returns Let `U` be
/// the result of `std::invoke(std::forward<F>(f), value())`. Returns a
/// `std::optional<U>`. The return value is empty if `*this` is empty,
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
/// is returned.
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
template < class F >
TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t< F, T & >
and_then(F &&f) &
{
using result = detail::invoke_result_t< F, T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
template < class F >
TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t< F, T & >
and_then(F &&f) &&
{
using result = detail::invoke_result_t< F, T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
template < class F >
constexpr detail::invoke_result_t< F, const T & >
and_then(F &&f) const &
{
using result = detail::invoke_result_t< F, const T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
template < class F >
constexpr detail::invoke_result_t< F, const T & >
and_then(F &&f) const &&
{
using result = detail::invoke_result_t< F, const T & >;
static_assert(detail::is_optional< result >::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: result(nullopt);
}
#endif
#endif
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) \
&& !defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
/// \brief Carries out some operation on the stored object if there is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. Returns a `std::optional<U>`. The return value is empty if
/// `*this` is empty, otherwise an `optional<U>` is constructed from the
/// return value of `std::invoke(std::forward<F>(f), value())` and is
/// returned.
///
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) &;
template < class F >
TL_OPTIONAL_11_CONSTEXPR auto
map(F &&f) &
{
return detail::optional_map_impl(*this, std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) &&;
template < class F >
TL_OPTIONAL_11_CONSTEXPR auto
map(F &&f) &&
{
return detail::optional_map_impl(std::move(*this), std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) const&;
template < class F >
constexpr auto
map(F &&f) const &
{
return detail::optional_map_impl(*this, std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) const&&;
template < class F >
constexpr auto
map(F &&f) const &&
{
return detail::optional_map_impl(std::move(*this), std::forward< F >(f));
}
#else
/// \brief Carries out some operation on the stored object if there is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. Returns a `std::optional<U>`. The return value is empty if
/// `*this` is empty, otherwise an `optional<U>` is constructed from the
/// return value of `std::invoke(std::forward<F>(f), value())` and is
/// returned.
///
/// \group map
/// \synopsis template <class F> auto map(F &&f) &;
template < class F >
TL_OPTIONAL_11_CONSTEXPR decltype(detail::optional_map_impl(
std::declval< optional & >(), std::declval< F && >()))
map(F &&f) &
{
return detail::optional_map_impl(*this, std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> auto map(F &&f) &&;
template < class F >
TL_OPTIONAL_11_CONSTEXPR decltype(detail::optional_map_impl(
std::declval< optional && >(), std::declval< F && >()))
map(F &&f) &&
{
return detail::optional_map_impl(std::move(*this), std::forward< F >(f));
}
/// \group map
/// \synopsis template <class F> auto map(F &&f) const&;
template < class F >
constexpr decltype(detail::optional_map_impl(
std::declval< const optional & >(), std::declval< F && >()))
map(F &&f) const &
{
return detail::optional_map_impl(*this, std::forward< F >(f));
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group map
/// \synopsis template <class F> auto map(F &&f) const&&;
template < class F >
constexpr decltype(detail::optional_map_impl(
std::declval< const optional && >(), std::declval< F && >()))
map(F &&f) const &&
{
return detail::optional_map_impl(std::move(*this), std::forward< F >(f));
}
#endif
#endif
/// \brief Calls `f` if the optional is empty
/// \requires `std::invoke_result_t<F>` must be void or convertible to
/// `optional<T>`. \effects If `*this` has a value, returns `*this`.
/// Otherwise, if `f` returns `void`, calls `std::forward<F>(f)` and returns
/// `std::nullopt`. Otherwise, returns `std::forward<F>(f)()`.
///
/// \group or_else
/// \synopsis template <class F> optional<T> or_else (F &&f) &;
template < class F, detail::enable_if_ret_void< F > * = nullptr >
optional< T > TL_OPTIONAL_11_CONSTEXPR
or_else(F &&f) &
{
if(has_value())
return *this;
std::forward< F >(f)();
return nullopt;
}
/// \exclude
template < class F, detail::disable_if_ret_void< F > * = nullptr >
optional< T > TL_OPTIONAL_11_CONSTEXPR
or_else(F &&f) &
{
return has_value() ? *this : std::forward< F >(f)();
}
/// \group or_else
/// \synopsis template <class F> optional<T> or_else (F &&f) &&;
template < class F, detail::enable_if_ret_void< F > * = nullptr >
optional< T >
or_else(F &&f) &&
{
if(has_value())
return std::move(*this);
std::forward< F >(f)();
return nullopt;
}
/// \exclude
template < class F, detail::disable_if_ret_void< F > * = nullptr >
optional< T > TL_OPTIONAL_11_CONSTEXPR
or_else(F &&f) &&
{
return has_value() ? std::move(*this) : std::forward< F >(f)();
}
/// \group or_else
/// \synopsis template <class F> optional<T> or_else (F &&f) const &;
template < class F, detail::enable_if_ret_void< F > * = nullptr >
optional< T >
or_else(F &&f) const &
{
if(has_value())
return *this;
std::forward< F >(f)();
return nullopt;
}
/// \exclude
template < class F, detail::disable_if_ret_void< F > * = nullptr >
optional< T > TL_OPTIONAL_11_CONSTEXPR
or_else(F &&f) const &
{
return has_value() ? *this : std::forward< F >(f)();
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \exclude
template < class F, detail::enable_if_ret_void< F > * = nullptr >
optional< T >
or_else(F &&f) const &&
{
if(has_value())
return std::move(*this);
std::forward< F >(f)();
return nullopt;
}
/// \exclude
template < class F, detail::disable_if_ret_void< F > * = nullptr >
optional< T >
or_else(F &&f) const &&
{
return has_value() ? std::move(*this) : std::forward< F >(f)();
}
#endif
/// \brief Maps the stored value with `f` if there is one, otherwise returns
/// `u`.
///
/// \details If there is a value stored, then `f` is called with `**this`
/// and the value is returned. Otherwise `u` is returned.
///
/// \group map_or
template < class F, class U >
U
map_or(F &&f, U &&u) &
{
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: std::forward< U >(u);
}
/// \group map_or
template < class F, class U >
U
map_or(F &&f, U &&u) &&
{
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: std::forward< U >(u);
}
/// \group map_or
template < class F, class U >
U
map_or(F &&f, U &&u) const &
{
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: std::forward< U >(u);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group map_or
template < class F, class U >
U
map_or(F &&f, U &&u) const &&
{
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: std::forward< U >(u);
}
#endif
/// \brief Maps the stored value with `f` if there is one, otherwise calls
/// `u` and returns the result.
///
/// \details If there is a value stored, then `f` is
/// called with `**this` and the value is returned. Otherwise
/// `std::forward<U>(u)()` is returned.
///
/// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u) &;
template < class F, class U >
detail::invoke_result_t< U >
map_or_else(F &&f, U &&u) &
{
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: std::forward< U >(u)();
}
/// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
/// &&;
template < class F, class U >
detail::invoke_result_t< U >
map_or_else(F &&f, U &&u) &&
{
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: std::forward< U >(u)();
}
/// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
/// const &;
template < class F, class U >
detail::invoke_result_t< U >
map_or_else(F &&f, U &&u) const &
{
return has_value() ? detail::invoke(std::forward< F >(f), **this)
: std::forward< U >(u)();
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
/// const &&;
template < class F, class U >
detail::invoke_result_t< U >
map_or_else(F &&f, U &&u) const &&
{
return has_value()
? detail::invoke(std::forward< F >(f), std::move(**this))
: std::forward< U >(u)();
}
#endif
/// \returns `u` if `*this` has a value, otherwise an empty optional.
template < class U >
constexpr optional< typename std::decay< U >::type >
conjunction(U &&u) const
{
using result = optional< detail::decay_t< U > >;
return has_value() ? result{u} : result{nullopt};
}
/// \returns `rhs` if `*this` is empty, otherwise the current value.
/// \group disjunction
TL_OPTIONAL_11_CONSTEXPR optional
disjunction(const optional &rhs) &
{
return has_value() ? *this : rhs;
}
/// \group disjunction
constexpr optional
disjunction(const optional &rhs) const &
{
return has_value() ? *this : rhs;
}
/// \group disjunction
TL_OPTIONAL_11_CONSTEXPR optional
disjunction(const optional &rhs) &&
{
return has_value() ? std::move(*this) : rhs;
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group disjunction
constexpr optional
disjunction(const optional &rhs) const &&
{
return has_value() ? std::move(*this) : rhs;
}
#endif
/// \group disjunction
TL_OPTIONAL_11_CONSTEXPR optional
disjunction(optional &&rhs) &
{
return has_value() ? *this : std::move(rhs);
}
/// \group disjunction
constexpr optional
disjunction(optional &&rhs) const &
{
return has_value() ? *this : std::move(rhs);
}
/// \group disjunction
TL_OPTIONAL_11_CONSTEXPR optional
disjunction(optional &&rhs) &&
{
return has_value() ? std::move(*this) : std::move(rhs);
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group disjunction
constexpr optional
disjunction(optional &&rhs) const &&
{
return has_value() ? std::move(*this) : std::move(rhs);
}
#endif
/// Takes the value out of the optional, leaving it empty
/// \group take
optional
take() &
{
optional ret = *this;
reset();
return ret;
}
/// \group take
optional
take() const &
{
optional ret = *this;
reset();
return ret;
}
/// \group take
optional
take() &&
{
optional ret = std::move(*this);
reset();
return ret;
}
#ifndef TL_OPTIONAL_NO_CONSTRR
/// \group take
optional
take() const &&
{
optional ret = std::move(*this);
reset();
return ret;
}
#endif
using value_type = T &;
/// Constructs an optional that does not contain a value.
/// \group ctor_empty
constexpr optional() noexcept : m_value(nullptr)
{
}
/// \group ctor_empty
constexpr optional(nullopt_t) noexcept : m_value(nullptr)
{
}
/// Copy constructor
///
/// If `rhs` contains a value, the stored value is direct-initialized with
/// it. Otherwise, the constructed optional is empty.
TL_OPTIONAL_11_CONSTEXPR
optional(const optional &rhs) noexcept = default;
/// Move constructor
///
/// If `rhs` contains a value, the stored value is direct-initialized with
/// it. Otherwise, the constructed optional is empty.
TL_OPTIONAL_11_CONSTEXPR
optional(optional &&rhs) = default;
/// Constructs the stored value with `u`.
/// \synopsis template <class U=T> constexpr optional(U &&u);
template < class U = T,
detail::enable_if_t< !detail::is_optional<
detail::decay_t< U > >::value > * = nullptr >
constexpr optional(U &&u) : m_value(std::addressof(u))
{
static_assert(std::is_lvalue_reference< U >::value,
"U must be an lvalue");
}
/// \exclude
template < class U >
constexpr explicit optional(const optional< U > &rhs) : optional(*rhs)
{
}
/// No-op
~optional() = default;
/// Assignment to empty.
///
/// Destroys the current value if there is one.
optional &operator=(nullopt_t) noexcept
{
m_value = nullptr;
return *this;
}
/// Copy assignment.
///
/// Rebinds this optional to the referee of `rhs` if there is one. Otherwise
/// resets the stored value in `*this`.
optional &
operator=(const optional &rhs) = default;
/// Rebinds this optional to `u`.
///
/// \requires `U` must be an lvalue reference.
/// \synopsis optional &operator=(U &&u);
template < class U = T,
detail::enable_if_t< !detail::is_optional<
detail::decay_t< U > >::value > * = nullptr >
optional &
operator=(U &&u)
{
static_assert(std::is_lvalue_reference< U >::value,
"U must be an lvalue");
m_value = std::addressof(u);
return *this;
}
/// Converting copy assignment operator.
///
/// Rebinds this optional to the referee of `rhs` if there is one. Otherwise
/// resets the stored value in `*this`.
template < class U >
optional &
operator=(const optional< U > &rhs)
{
m_value = std::addressof(rhs.value());
return *this;
}
/// Constructs the value in-place, destroying the current one if there is
/// one.
///
/// \group emplace
template < class... Args >
T &
emplace(Args &&... args) noexcept
{
static_assert(std::is_constructible< T, Args &&... >::value,
"T must be constructible with Args");
*this = nullopt;
this->construct(std::forward< Args >(args)...);
}
/// Swaps this optional with the other.
///
/// If neither optionals have a value, nothing happens.
/// If both have a value, the values are swapped.
/// If one has a value, it is moved to the other and the movee is left
/// valueless.
void
swap(optional &rhs) noexcept
{
std::swap(m_value, rhs.m_value);
}
/// \returns a pointer to the stored value
/// \requires a value is stored
/// \group pointer
/// \synopsis constexpr const T *operator->() const;
constexpr const T *operator->() const
{
return m_value;
}
/// \group pointer
/// \synopsis constexpr T *operator->();
TL_OPTIONAL_11_CONSTEXPR T *operator->()
{
return m_value;
}
/// \returns the stored value
/// \requires a value is stored
/// \group deref
/// \synopsis constexpr T &operator*();
TL_OPTIONAL_11_CONSTEXPR T &operator*()
{
return *m_value;
}
/// \group deref
/// \synopsis constexpr const T &operator*() const;
constexpr const T &operator*() const
{
return *m_value;
}
/// \returns whether or not the optional has a value
/// \group has_value
constexpr bool
has_value() const noexcept
{
return m_value != nullptr;
}
/// \group has_value
constexpr explicit operator bool() const noexcept
{
return m_value != nullptr;
}
/// \returns the contained value if there is one, otherwise throws
/// [bad_optional_access]
/// \group value
/// synopsis constexpr T &value();
TL_OPTIONAL_11_CONSTEXPR T &
value()
{
if(has_value())
return *m_value;
throw bad_optional_access();
}
/// \group value
/// \synopsis constexpr const T &value() const;
TL_OPTIONAL_11_CONSTEXPR const T &
value() const
{
if(has_value())
return *m_value;
throw bad_optional_access();
}
/// \returns the stored value if there is one, otherwise returns `u`
/// \group value_or
template < class U >
constexpr T
value_or(U &&u) const &
{
static_assert(std::is_copy_constructible< T >::value
&& std::is_convertible< U &&, T >::value,
"T must be copy constructible and convertible from U");
return has_value() ? **this : static_cast< T >(std::forward< U >(u));
}
/// \group value_or
template < class U >
TL_OPTIONAL_11_CONSTEXPR T
value_or(U &&u) &&
{
static_assert(std::is_move_constructible< T >::value
&& std::is_convertible< U &&, T >::value,
"T must be move constructible and convertible from U");
return has_value() ? **this : static_cast< T >(std::forward< U >(u));
}
/// Destroys the stored value if one exists, making the optional empty
void
reset() noexcept
{
m_value = nullptr;
}
private:
T *m_value;
}; // namespace tl
} // namespace tl
namespace std
{
// TODO SFINAE
template < class T >
struct hash< tl::optional< T > >
{
::std::size_t
operator()(const tl::optional< T > &o) const
{
if(!o.has_value())
return 0;
return std::hash< tl::detail::remove_const_t< T > >()(*o);
}
};
} // namespace std
#endif
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